Control of the morphology and size of magnetite particles with peptides mimicking the Mms6 protein from magnetotactic bacteria

2010 ◽  
Vol 343 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Atsushi Arakaki ◽  
Fukashi Masuda ◽  
Yosuke Amemiya ◽  
Tsuyoshi Tanaka ◽  
Tadashi Matsunaga
Keyword(s):  
Magnetotactic Bacteria ◽  
Magnetite Particles

scholarly journals S-band ferromagnetic resonance spectroscopy and the detection of magnetofossils

2013 ◽  
Vol 10 (80) ◽  
pp. 20120790 ◽  
Author(s):  
Andreas U. Gehring ◽  
Jessica Kind ◽  
Michalis Charilaou ◽  
Inés García-Rubio
Keyword(s):  
Ferromagnetic Resonance ◽  
Uniaxial Anisotropy ◽  
Magnetotactic Bacteria ◽  
Time Frame ◽  
Resonance Spectroscopy ◽  
Verwey Transition ◽  
Geological Time ◽  
Change Of Direction ◽  
X Band ◽  
Magnetite Particles

We report the use of S-band ferromagnetic resonance (FMR) spectroscopy to compare the anisotropic properties of magnetite particles in chains of cultured intact magnetotactic bacteria (MTB) between 300 and 15 K with those of sediment samples of Holocene age in order to infer the presence of magnetofossils and their preservation in a geological time frame. The spectrum of intact MTB at 300 K exhibits distinct uniaxial anisotropy because of the chain alignment of the cellular magnetite particles and their easy axes. This anisotropy becomes less pronounced upon cooling and below the Verwey transition ( T V ) it is nearly vanished mainly owing to the change of direction of the easy axes. In a natural sample, magnetofossils were detected by uniaxial anisotropy traits similar to those obtained from cultured MTB above T V . Our comparative study emphasizes that indispensable information can be obtained from S-band FMR spectra, which offers even a better resolution than X-band FMR for discovering magnetofossils, and this in turn can contribute towards strengthening our relatively sparse database for deciphering the microbial ecology during the Earth's history.

scholarly journals Critical superparamagnetic/single-domain grain sizes in interacting magnetite particles: implications for magnetosome crystals

2008 ◽  
Vol 6 (41) ◽  
pp. 1207-1212 ◽  
Author(s):  
Adrian R. Muxworthy ◽  
Wyn Williams
Keyword(s):  
Magnetotactic Bacteria ◽  
Thermal Fluctuations ◽  
Single Domain ◽  
Magnetic Interactions ◽  
Threshold Size ◽  
Grain Sizes ◽  
Magnetite Particles

Magnetotactic bacteria contain chains of magnetically interacting crystals (magnetosome crystals), which they use for navigation (magnetotaxis). To improve magnetotaxis efficiency, the magnetosome crystals (usually magnetite or greigite in composition) should be magnetically stable single-domain (SSD) particles. Smaller single-domain particles become magnetically unstable owing to thermal fluctuations and are termed superparamagnetic (SP). Previous calculations for the SSD/SP threshold size or blocking volume did not include the contribution of magnetic interactions. In this study, the blocking volume has been calculated as a function of grain elongation and separation for chains of identical magnetite grains. The inclusion of magnetic interactions was found to decrease the blocking volume, thereby increasing the range of SSD behaviour. Combining the results with previously published calculations for the SSD to multidomain threshold size in chains of magnetite reveals that interactions significantly increase the SSD range. We argue that chains of interacting magnetosome crystals found in magnetotactic bacteria have used this effect to improve magnetotaxis.

A New Method for Direct Determination of the Recoilless Fraction with Application to Magnetic Nanoparticles

2002 ◽  
Vol 721 ◽  
Author(s):  
Monica Sorescu
Keyword(s):  
Room Temperature ◽  
Average Particle Size ◽  
Direct Determination ◽  
Average Particle ◽  
Lattice Method ◽  
Recoilless Fraction ◽  
Single Room ◽  
Magnetite Particles ◽  
Physical Mixtures

AbstractWe propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19 nm.

Tuning the Magnetic Vortex State in Magnetite Nanodiscs for Remote Control of Biological Signalling

2019 ◽  
Author(s):  
Danijela Gregurec ◽  
Alexander W. Senko ◽  
Andrey Chuvilin ◽  
Pooja Reddy ◽  
Ashwin Sankararaman ◽  
...  
Keyword(s):  
Remote Control ◽  
Ion Channels ◽  
Ground State ◽  
Magnetic Particles ◽  
Colloidal Stability ◽  
Vortex State ◽  
Magnetic Vortex ◽  
Electron Holography ◽  
Dipole Interactions ◽  
Magnetite Particles

In this work, we demonstrate the application of anisotropic magnetite nanodiscs (MNDs) as transducers of torque to mechanosensory cells under weak, slowly varying magnetic fields (MFs). These MNDs possess a ground state vortex configuration of magnetic spins which affords greater colloidal stability due to eliminated dipole-dipole interactions characteristic of isotropic magnetic particles of similar size. We first predict vortex magnetization using micromagnetic stimulations in sub-micron anisotropic magnetite particles and then use electron holography to experimentally investigate the magnetization of MNDs 98–226 nm in diameter. When MNDs are coupled to MFs, they transition between vortex and in-plane magnetization allowing for the exertion of the torque on the pN scale, which is sufficient to activate mechanosensitive ion channels in cell membranes.<br>

Thermal fluctuations of non-motile magnetotactic bacteria in AC magnetic fields

2008 ◽  
Vol 44 (3) ◽  
pp. 223-236 ◽  
Author(s):  
K. Ērglis ◽  
L. Alberte ◽  
A. Cēbers
Keyword(s):  
Magnetic Fields ◽  
Magnetotactic Bacteria ◽  
Thermal Fluctuations

Sorption of Water Soluble Organic Dyes on Magnetic Poly(oxy-2,6-dimethyl-1,4-phenylene)

1995 ◽  
Vol 60 (9) ◽  
pp. 1448-1456 ◽  
Author(s):  
Ivo Šafařík ◽  
Miroslava Šafaříková ◽  
Vlasta Buřičová
Keyword(s):  
Organic Compounds ◽  
Azo Dye ◽  
Organic Dyes ◽  
Water Soluble ◽  
Magnetic Composite ◽  
Water Solutions ◽  
Magnetite Particles

Magnetic composite based on poly(oxy-2,6-dimethyl-1,4-phenylene) (PODMP) was prepared by melting the polymer with ε-caprolactam in a presence of fine magnetite particles. Magnetic PODMP was used for sorption of water soluble organic compounds (dyes belonging to triphenylmethane, heteropolycyclic and azo dye groups) from water solutions. There were considerable differences in the binding of the dyes tested. In general, heteropolycyclic dyes exhibited the lowest sorption.

scholarly journals Mass collection of magnetotactic bacteria from the permanently stratified ferruginous Lake Pavin, France

2021 ◽  
Author(s):  
Vincent Busigny ◽  
François P. Mathon ◽  
Didier Jézéquel ◽  
Cécile C. Bidaud ◽  
Eric Viollier ◽  
...  
Keyword(s):  
Magnetotactic Bacteria ◽  
Lake Pavin ◽  
Mass Collection

scholarly journals Application of modified green algae Nannochloropsis sp. as adsorbent in the simultaneous adsorption of Methylene Blue and Cu(II) cations in solution

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Buhani ◽  
Tri Agus Wijayanti ◽  
Suharso ◽  
Sumadi ◽  
Muslim Ansori
Keyword(s):  
Heavy Metals ◽  
Methylene Blue ◽  
Green Algae ◽  
Contact Time ◽  
Organic Dyes ◽  
Silica Matrix ◽  
Particle Coating ◽  
Adsorption Data ◽  
Magnetite Particles ◽  
Simultaneous Sorption

AbstractBiomass of algae is a very potent adsorbent for absorbing aqueous waste containing heavy metals and organic dyes. This study purposes to confirm the ability of adsorbents from green algae Nannochloropsis sp. modified with silica (ASN) and followed by coating magnetite particles (ASN-MPs) to absorb simultaneously the mixture of Methylene Blue (ME) and Cu(II) cations in aqueous solution. Simultaneous sorption of ME and Cu(II) cations to ASN and ASN-MPs was carried out by the batch method with the interaction pH condition 7, contact time 90 min, and initial concentrations of ME and Cu(II) cations (0.1–1.0 mM). Based on adsorption data, Cu(II) cations have a greater adsorption rate and capacity (qm) compared to ME at the same contact time and initial concentration. The adsorption capacity (qm) values of the bi-component ME and Cu(II) cation mixture in ASN and ASN-MPs were 1.39 × 10− 1 and 5.32 × 10− 1 mmol g− 1, respectively, with the binary Langmuir adsorption isotherm constant for Cu(II) cations greater than ME. Modified adsorbent from algae Nannochloropsis sp. with silica matrix and magnetite particle coating is an adsorbent that has a high effectiveness in the collective sorption of ME and Cu(II) cations. Therefore, these adsorbents can be used for the adsorption of cation mixtures of heavy metals and organic dyes that are cationic in solution.

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